Land salinization is a global problem faced by the mankind China has a large area of salinized land, which is mainly distributed in the North China Plain, the Northeast Plain, the inland of the Northwest, and the coastal regions. The survival rate of plants grown in saline-alkaline soils is generally very low, thus seriously affecting China's agricultural and forestry production.
Too much salt in the soil results in salt damage, which affects normal growth of plants. Salinity causes harms to plants in two ways: first, poisoning, when plants absorb a large quantity of sodium or chloride ions, the structure and the function of the cell membrane change, which ultimately causes plant death; second, improving the osmotic pressure of the soil, which inhibits the absorption of the plant roots, so that it is difficult for the plant to absorb water, cell dehydration and plant wilting occur, and finally plant death is resulted. Therefore, reasonable use of saline land, complete amelioration of the saline-alkaline land, and cultivation of varieties of salt-resistant plants are future developing directions.
At present, the distribution of saline-alkaline land in China is as follows:
1. Saline-alkaline lands in Northwest inland include: most parts of Xinjiang, Qaidam Basin in Qinghai, Hexi Corridor in Gansu, and western Inner Mongolia.
2. The semi-arid Saline-alkaline lands of the upper and middle reaches of the Yellow River include: Qinghai, eastern Gansu, Ningxia, Inner Mongolia, the Hetao region, Shaanxi, and valley plains in Shanxi.
3. Arid and semi-arid depression saline-alkaline lands in Huanghuaihai Plain include: the lower reaches of the Yellow River, the Haihe River Plain, Huanghuai plain, across Beijing-Tianjin-Hebei-Shandong-Henan and northern Anhui northern Jiangsu.
4. Semi-humid semi-arid low-lying saline-alkaline lands in the Northeast include: including the Songnen Plain, Liaoxi Basin, Sanjiang Plain, and Hulunbeir area.
5. Coastal semi-humid saline-alkaline lands include: including east, south and Jiangbei coastal areas.